Oil-relieved geneva movement



May 25, 1943. BRENKERT 2,320,064

OIL-RELIEVED GENEVA MOVEMENT Filed Aug. '7, 1941 INVENTOR. A7964 flax(aw? Patented May 25, 1943.

vOIL-RELIEVED' GENEVA MOVEMENT Karl Brenkert, Detroit, Mich, assignor toBrenlrert Light Projection Company, Detroit, Mich.

Application August '7, 1941, Serial No. 405,776 Claims. (01. 74-43 I Thepresent invention pertains to the Geneva or intermittent movement ofmotion picture apparatus and particularly to the reduction of noise inthe intermittent movement.

In modern commercial motion picture ma chines, particularly projectors,the intermittent movement runs in a bath of oil or is drenched with oil.The cam of the Geneva movement has an arcuate portion that registerswith concave faces in the star wheel for holding the wheel stationarybetween movements. At the end of each movement, however, an end of oneof the concave faces, or a finger, strikes the arcuate cam portion withconsiderable force. Due to the method of lubrication described above, afilm of oil is-trapped in the area of the impact. I have discovered thatthe pounding that occurs in even an accurately machined Geneva mechanismis due to the trapped film of oil, and that the pounding can beeliminated or reduced if the oil film can be removed rapidly from theimpact area.

The principal object of this invention is to reduce or eliminatepounding or oil knock and is accomplished by providing a means of rapidescape of the oil film. In the preferred construction an oil reliefpassage is provided in the form of a port through the arcuate camportion or fiange at the area of greatest impact. The oil relief meansmay however take other forms. For example, the free ends of the starwheel fingers may be relieved on the concave side to provide a clearancethrough whichthe oil film escapes.

The pounding is most severe where the arcuate cam portion is engaged bythe'outer ends of the star Wheel fingers, since it is here that thevelocity of the star wheel is greatest and the oil has the least time toescape. Accordingly, the

oil relief is provided in the regionrwhere the arcuate'cam portion isengaged by the outer ends of the star wheel fingers. This'arrangementremoves one of the serious objections to a. large star wheel whileretaining its principal advan-' tage of accurate indexing within thesmall permissible manufacturing tolerance.

In a co-pending application Serial No. 405,775,

filed August 7, 1941, I have disclosed the tapering of the free ends ofthe star wheels for the purpose of reducing inertia and wear. Suchtapered fingers also play a part in the elimination of oil knock sincethey reduce the inertia of the fingers during the impact and present areduced impacting area and hence a smaller trapped oil film. a 5

The invention is fully disclosed by way of example in the followingdescription and in the accompanying drawing in which:

Figure 1 is an elevation, partly insection, of the Genevamovement nearthe end of the motion of the star wheel;

Figure 2 is a section on the line' 2-2 of Figure 1;

Figure 3 is a view, similar to Figure 1, at the end of the motion of thestar wheel;

Figure 4 is an enlarged detail of Figure 3; Figure 5 is a perspectiveview of the cam; Figure 6 is a section on the line 6-6 of Figure 5, andv V Figure '7 is an elevation, partly in section, of the feed sprocketshaft assembly.

Reference to these views will now be made by .use of like characterswhich are employed to designate corresponding parts throughout;

The star wheel I is formed with a number of radial slots 2, and betweeneach pair of adjacent slots isan arcuate concave-face 3. As a result ofthis construction, eachslot and the adjacent faces 3 forms a pairoffingers or prongs 4. On

one side of the star wheel there is preferably formed a hub 5 formounting on a shaft (5 which carries the usual intermittent sprocketwheel I. r

A number of holes 8 are drilled through the star wheel to reduce'itsweight in accordance with ments or while the pin 12 is out of the slots.The locking flange I3 is relieved at M for about A 45 to either side ofthe pin to permit the star wheel fingers 4 to enter, as in the wellknown Geneva action. Up to this point the construction is conventional.-

"As previously stated, this'mechanism is thoroughly lubricated, and allexposed surfaces are covered with a film of oil. When the star wheelfingers approach and strike the flange-l3, the V trapping of the oilfilm between these parts results in a poundin'gaction or knock.' This isespecially true of modern commercial machines Where the clearance ofabout .0002 inch between the parts is insufiicient to permit a rapidescape of the oil film.

According to the invention, a relief means is provided for rapid escapeof the oil film without exceeding the above mentioned manufacturingtolerance. One form of such relief consists of a port I 5 through theflange l3 at the area engaged 5 by the approaching star wheel finger.This area is spaced from the cam pin I2, in the counter direction of camrotation, slightly less than the distance between the outer ends ofsuccessive slots 2. A similar slot I6 is cut through the flange IS anequal distance from the cam pin l2 in the opposite direction, for thepurpose of maintaining the balance of the cam. When a star wheel fingercompletes its impact on the flange I3, the intervening oil film is halfthe usual thickl ness because there is no trapped film over-the port I5.Also, the film on the finger mayrescape; through the port and is nottrapped between the contacting parts. The relief is completed throughtheopening 14, andthrough-the open vertical side of the flange l3 asillustrated in Figures 2- .and 5.

The described locationof the port 15 is a-mat- P ter ofconsider-ed.selection lt is in;this area that the time permittedordinarilyforthe-escapa of the oil film igthe least, because this areais engaged bys h m st rapi ly movin :pQ tiQ i of the star wheel. Thus,the oil relief meansjs be the heaviest. It is desirable to space therelief means somedistance frorn the; portion of the flange l3engagedgbyl theme e w 1 1 n *1 Gave faces n. order to main a n-the so iflan at this portion, Where the most secure locking 0?, the star wheelbetween :movementsis obtained. n-

In the modification shown in Figure 4, the g i outer ends of thestarwheel fingers arerelievegi about .003 inch on the oncave ;1. cesby;in- V creasing. the radius, as indicated by the numeral [1. Thisclearanceprovidesirelief of the oil film at the critical poin t,; 40 Inmy sci-pending app a ion. I h ve d ib d. 1-;

th taperin tof the, st rxwheel fin ers tqw rds their free.;ends .and onthe lateral, facesof the;- star wheel, as, indicated; by the. numeral;1l 8, i fo r the purpose vof reducing the i rtia of" the rnech anism.This construction ;also contributesto the;

impactforceandimpact area- ;z

It has been D DO JtQL-HSQ a ma e St t;-

wheel in .order to eliminate thenoise in a larger mechanism. The largermechanisms; 3 however has t e advant seotm re accur t inde ne ndtolerances; The; present invention retains this advantage while Ieliminating the objection .due

to the oil knock, In the construction shown, the star wheel has anoverall Width of '1.96.5 inches. and. the wheelifingers overlap theports 15 and I6 by .inc h to prevent snaggingnof the fingers in theports, I L

Although specific embodiments of the invention havebeen illustrated and,described, .it-will be understood that various alterations in the details of construction nay be made Without depar om: the-sc e; o the v ntonv s in cated byn h n dp aim t 1 What I claim is:

1. In an intermittent Geneva movement -comprising a star, wheelmemberhaving radial slots and intervening-concave faces formin fin e arcuatelocking flange :;adapted,-;to;=register with said facespsaidflangehaving anz opening there-.1:

"through disposed at adistance-from, saidzpin, in=

y't-he counter -direction ofr cam rotation,-- slightly less than, andmore than? half. the distance-bestar wheel, the circumferential:dimension of said provided ,Where, the pounding would; otherwise may betrapp d b twe n :s ,-flanseand;the .Gnr

:a free fluid outlet in1addition; to; said opening; .whereby,saidopening delivers oil'away fromthe r vening concave faces forming ;a ;finger rat: each through so I positioned. thatgsaidreconcave :faces asuccessively-,overlap said opening -c ompletely;;as

ferential dimension of said, opening beingsufIi-r;eliminationr'ofgtheoilrknock sinceit reduces the;

uprising a star-wheel member having-radial;slots: I andintervening-concave faces-forming airfingerf a steadier picture given-rnanufacturing at each side of each slot, and a cam member having a pinadapted to enter said slots and an arcuate locking flange adapted toregister with said faces; said flange having an opening therethroughdisposed at a distance from said pin, in the counter direction of camrotation, slightly less than the distance between the outer ends ofsuccessive slots of said star wheel, the circumferential dimension-ofsaid opening cbeing sufficient to relieve any oil that may be trappedbetween said flange and the engaging concave face, said arcuate flangehaving a free fluid outlet in addition to said opening, whereby saidopen- :prising a ,starbwheel member having radial slots and intervening,concave faces forming a finger ateach side of each slot, and a cammember having apinadapted to: enter said slots and-.an 1:, 1'

opening being; sufiioientyto-relieve, any-oil that a gaging concaveface, saidarcuate -flange.:ghaving outer ends ofsaidrfaces asmesh-engage said open-.

.ing.

.3. In anlintermittentjGeneya mQVement' 'ex posed f or external;lubrication. and,; compr ising; :a star Wheel member havingrradial-vslotsand -inter-: .l

i o each slo iend a; camlmember; having a: pin adapted tqienter:said-slots andan arcuate locking flange adapted to register with saidfaces; said flan e-havin an o l: r lief-z opening ,,there-' id p nrleves the: re pective slots, the; circumcient to relieve;;any:.oiL thatmay: be trapped been 7 l. tween said flange: and;vthe;:engaging:;concave; face. v

1 4. In aminte mi ent: Geneva moyement com- .1

at each side of each slot, and a cam member bl-av in a pin p e ;toenter; saidslotsandcaan arcuate porti n ad pte ;.to;rr.eg:isterwith-said: faces; said fingers; beingrelieved at theirqfree ends byanincreased'radius in saidconcave facesi- 3 at said ends, :tolprovide aslight clearancefrom.

said arcuate portion. I

5. In an. intermittent Geneva movement com-,

1 prising astarwheelmmember having. radial slotsf and interveningconcaxre faces forming-a .finger 4 at each side of, each slot,,,.said ffaces being err-e,

gageableby an arcuate camgnember, said fingers;

being relieved at their free endsjby an'jincreasedj radius in saidconcave faces at said venjds;;to provide a slight clearancewhensaid-faces areenaged by said cam-member.--

KARL BRENKERTJ

